The invention is based on a fuel injection pump for internal combustion engines as defined hereinafter.
A fuel injection pump of this type is known from German Patent Application 39 20 459 A1. This fuel injection pump has a pump piston, guided in a cylinder bore, and defining a pump work chamber, the pump piston being fed into simultaneously rotating and reciprocating motion by a drive mechanism. During a given intake stroke and during a controlled portion of the supply stroke of the pump piston, the pump work chamber can be made to communicate, via a connection controlled by an electric valve, with a suction chamber serving as a fuel reservoir. Via a distributor opening disposed in a distributor, the pump work chamber can be made to communicate during a given supply stroke of the pump piston, with one of a plurality of pressure conduits which communicate via injection lines with the injection locations at the engine. The pumping of fuel under high pressure is determined by the closing phase of the valve.
To pump fuel into the suction chamber, a separate feed pump is necessary, which means major engineering effort and expense. The drive mechanism for the pump piston is disposed in the suction chamber and is surrounded by diesel fuel, which serves to lubricate the drive mechanism. However, at high injection pressures the lubricating action of the fuel is no longer sufficient, so that damage to the drive mechanism can occur. For use with Otto internal combustion engines, the known fuel injection pump is unsuitable since the Otto-type fuel has no lubricating action, and because of its disposition in the suction chamber the drive mechanism cannot be lubricated with oil, since the oil would get into the fuel.